Industrial control relay

ABSTRACT

An electromagnetic switching device having a plurality of switch modules mounted within a housing. A stationary magnet is positioned within an opening in an operating coil, and both the magnet and the coil are mounted within the housing. A movable magnet, having a pair of pole faces, is mounted for reciprocal movement between an energized and a deenergized position within the housing. A one piece rigid member is fixed to the pole faces of the movable magnet so as to form a pole shader therefor. The rigid member has rigid arms extending in the direction of movement of the movable magnet for guiding the movable magnet in the housing between the energized and deenergized positions. Actuator sections extending from the arms of the rigid member at points distant from the pole faces of the movable magnet and cause actuation of the switch modules when the operating coil of the device is energized.

United States Patent Hardman et al.

a [451 Aug. 27, 1974 INDUSTRIAL CONTROL RELAY [73] Assignee: General Electric Company, New

York, NY.

[22] Filed: July 30, 1973 [21] Appl. No.: 383,685

[52] US. Cl 335/99, 335/198, 335/245 [51] Int. Cl. H0lh 51/30 [58] Field of Search 335/99, 103, 104, 105,

335/198, 193, 24 S, 243, 247, 249, 251; 200/166 BC, 166 H Primary Examiner-Harold Broome Attorney, Agent, orFirm-S. A. Young; P. L. Schlamp; R. G. Simkins [57] ABSTRACT An electromagnetic switching device having a plurality of switch modules mounted within a housing. A stationary magnet is positioned within an opening in an operating coil, and both the magnet and the coil are mounted within the housing. A movable magnet, having a pair of pole faces, is mounted for reciprocal movement between an energized and a deenergized position within the housing. A one piece rigid member is fixed to the pole faces of the movable magnet so as to form a pole shader therefor. The rigid member has rigid arms extending in the direction of movement of the movable magnet forguiding the movable magnet in the housing between the energized and deenergized positions. Actuator sections extending from the arms of the rigid member at points distant from the pole faces of the movable magnet and cause actuation of the switch modules when the operating coil of the device is energized.

20 Claims, 8 Drawing Figures 1 INDUSTRIAL CONTROL RELAY BACKGROUND OF THE INVENTION and more particularly to an electromagnetic switching device having a plurality of switch modules mounted within a housing.

2. Description of the Prior Art When an AC relay is energized, its movable magnet travels toward and contacts a stationary magnet. The alternating current in the operating coil of the relay normally causes a vibration due to movement between the movable and stationary magnets. In order to eliminate the vibration in the relay, pole shaders in the form of small non-structural members made of metal such as copper, brass, aluminum or steel are attached to .the pole faces of the movable or stationary megnets to provide somewhat less than 90 out of phase magnetic flux. This out of phase magnetic flux keeps the movable and stationary magnets in contact when the coil is energized and eliminates the vibration between the magnets. Since the pole shaders are non-structural pieces they are often mechanically staked to the pole faces of the movable or stationary magnet. Under these circumstances, and due to constant impact of the pole faces of the movable magnet against the stationary magnet, the pole shaders can loosen or break so as to causethe relay to again vibrate when the coil is energized. More permanent attachment of the small non-structurally shaped pole shaders to the pole faces by use of adhesives is slow, cumbersome and costly.

These relays generally contain one or more switch modules which are mounted in the relay housing. Each switch module includes a pair of stationary contacts, an actuating plunger, a movable contact bridge, a tip force spring, and a pair of movable contacts attached to the opposite ends of the contact bridge and in juxtaposition with the stationary contacts so as to move into and out of engagement therewith upon actuation and deactuation of the relay. When the actuating plunger and contact bridge carry the movable contacts into engagement with the stationary contacts, contact bounce in the form of a damped oscillation developes between the movable and stationary contacts until they are in final engagement. Prolonged contact bounce causes excessive arcing and contact erosion, thus ultimately resulting in contact sticking and failure of the switch module.

Furthermore, if a switch module has reversiblecontact modes such that when it is mounted in the relay housing in a first position, the switch contacts are normally open, and when the module is inverted within the housing the switch contacts are normally closed, it is difficult for one to know whether the module is mounted in a normally open or a normally closed contact mode when the assembledrelay is visually examined. Therefore in order to aid in the identification of the contact mode of switch modules mounted within.

a relay housing, a portion of the external terminals of each switch module isv painted to provide a visual indication. Painting of a portion of the external terminals of the switch module is a sloppy, time consuming, and costly operation.

OBJECTS OF THE INVENTION It is therefore an object of this invention to provide an improved relay having none of the disadvantages mentioned above.

It is another object of this invention to provide an AC relay having a one piece multifunction member of sufficient structural strength serving in part as a larger more effective pole shader.

It is another object of this invention to provide a switch module having improved contact life by reducing the arcing caused by contact bounce.

It is another object of thisinvention to provide an improved housing for a switch module having a permanent visual indication of the contact mode of the module.

It is another object of the invention to prevent operation of the entire relay if one of the switch modules fails due to contact sticking.

Other objects of the invention will be pointed out hereinafter.

SUMMARY OF THE INVENTION In accordance with abroad aspect of the invention there is provided an electromagnetic switching device having a plurality of switch modules mounted in a housing. Each switch module includes a pair of stationary contacts, an actuating plunger movable within and extending from the modules enclosure, a movable contact bridge slidably attached to the actuating plunger, and a pair of movable contacts attached to each opposite end of the contact bridge and in juxtaposition with a respective one of the stationary contacts. The ends of the contact bridge are unsymmetrically bifurcated so that one movable contact attached to one cantilevered finger at the'bifurcated end of the contact bridge is significantly unequal in mass to the adjacent movable contact attached to the adjacent cantilevered finger at the same bifurcated end of the contact bridge. The difference in mass of the adjacent movable contacts reduces the chance that the contact bounce of both contacts at either end of the bridge is synchronized so as to increase the probability that the switch closure of the module occurs as fast as possible, and with as little contact arcing as possible.

The contact mode of each switchmodule is convertible so that when a switch module is placed in the housing of the relay in oneposition, the module is in the normally open contact mode, and when the switch module is inverted in the relay housing the module is in the normally closed contact mode. The enclosure for the switch module is provided with a protrusion extending from an end surface thereof. This protrusion has a different color than the end surface so that the user of the relay can visually observe whether the switch module is in the normally opened or normally closed contact mode when assembled in the relay.

The relay further includes a stationary magnet positioned within a slot in an operating coil of the relay. A movable magnet is mounted within the housing of the relay for reciprocal movement between an energized and a deenergized position. A one piece rigid member has a portion thereof fixed to the pole faces of the movable magnet so as to form a structurally secure pole shader therefore. The rigid member also has rigid arms extending in the direction of movement of the movable magnet for guiding the movable magnet between the energized and deenergized positions within the housing. Actuator sections extend from the arms of the rigid member for actuating a yoke when the device is energized. The yoke has raised sections, such that each of the raised sections engages one end of a respective actuating plunger of respective switch module so that all the switch modules are actuated simultaneously when the relay is energized. A one piece spring loaded yoke cover ispositioned adjacent the opposite end of each of the actuating plungers so as to deactuate all the switch modules simultaneously when the relay is deenergized.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front view of adeenergized relay wherein portions of the housing have been cut away to show the actuating elements of the relay and the switch module which is in a normally closed contact mode;

FIG. 2 is a front view of the relay shown in FIG. 1 wherein the relay is energized;

FIG. 3 is a side sectional view of a portion of the rela shown in FIG. 1 depicting the elements which actuate the switch modules; v

FIG. 4 is anexploded perspective view of the actuating elements shown in FIG. 3;

FIG. 5 is a front view of a switch module positioned in the normally open contact mode;

FIG. 6 is a front view of a switch module positioned in the normally closed contact mode; I

FIG. 7 is a top view of a contact bridge of a switch module showing opposite ends of the contact bridge to be unsymmetrically bifurcated, and each of the adjacent movable contacts attached to the cantilevered bridge fingers being of unequal mass; and I FIG. 8 is an end view of the contact bridge and attached movable contacts shown in FIG. 7.

DESCRIPTION OF A PREFERRED EMBODIMENT The invention will now be explained with reference to FIGS. l-7.

As shown in FIG. 1, a relay 10 is comprised of a metal base plate 12, a pair of molded plastic lower half sections 14a and 14b, a molded plastic upper housing section 16 and a molded housing cover 18. For illustrative purposes the front end portion of lower molded half section 14b is shown cut away. Lower molded half section 14a is fastened to base plate 12 using standard fastening techniques such as threaded fasteners, not shown.

A U-shaped movable magnet 20, shown in perspective in FIG. 4, has a base 22 and a pair of legs 24a and 24b extending from the base. End comer'portions 26a and 26b of base 22 are bevel shaped. A passage 28 extends through the base of magnet from its front to its rear face. Magnet 20 has pole faces 30a and 30b at the respective ends of legs 24a and 24b, and slots 32a and 32b extend from respective pole faces 30a and 30b into respective legs 24a and 24b.

Also shown in FIG. 4 is a one piece rigid U-shaped structural member 34 made of suitable structural material, such as steel, Member 34 is comprised of a pair of arms 36a and 36b interconnected by a pair of respective base frame members 38a and 38b. Arms 36a and 36b have respective rectangular shaped windows40a flanged sections 44a and 44b, which extend from opposite ends of main section 42 at approximately right angles thereto, provide additional structural strength to the member. Similarly window 40b is formed within a main section 46 of am 36b wherein respective flanged sections 48a and 48b, which extend from opposite ends of main section 46 at approximately right angles thereto, provide additional structural strength to the member. Slots 50a and 50b extend from the respective top surfaces and inner edges of respective top sections 52a and 52 b of respective base frame members 38a and 38b. Again to increase the rigidity and structural strength of member 34, flanged sections 54a and 54b extend from respective outer edges of respective top sections 52a and 52b of respective base frame members 38a and 38b and at approximately right angles to respective sections 52a and 52b. L-shaped actuator sections 56a, and 56b extend upward from the top of respectivemain sections 42 and 46 of respective arms 36a and 36b and away from respective base frame members 38a and 38b.

Rigidmember 3.4 is fixed to movable magnet 20 as follows Lower ledges 58a and 58b, which are located adjacent and below respective windows 40a and 40b and are part of respective main sections 42 and 46 of respective arms 36a and 36b of rigid member 34, are located within respective slots 32a and 32b in respective legs 24a and 24b of magnet 20 to form the pole shader within respective pole faces 30a and 30b. Slots 50a and 50b in respective top sections of respective base frame members 38a and 38b are so positioned adjacent passage 28 in the base of movable magnet 20 that a flat spring 60 can be extended through passage 28 until its opposite ends fit within respective slots 50a and 50b and press rigid member 34 downward to lock it to movable magnet 20.

A standard relay operating coil 62 having external current carrying terminals 64a and 64b and an opening 66 extending therethrough is positioned between respective arms 36a and 36b of rigid member 34 so that slot 66 in coil 62 is aligned with respective windows 40a and 40b of the arms of the rigid member. A stationary magnet 68 is placed within opening 66 of coil 62 wherein opposite ends of stationary magnet 68 extend through respective windows 40a and 40b of the arms of the rigid member and have grooves 70a and 70b (shown in FIG. 3) formed therein.

After lower molded half section 14a is fastened to base plate 12, the assembly comprising the movable magnet, rigid member, operating coil and stationary magnet is positioned adjacent base plate 12 such that one end 72 of operating coil 62 rests on a ledge 74 of a window 76 formed within a side wall 78 of lower molded half section 14a as shown in FIG. 2. Furthermore, half of each respective groove 70a and 70b of stationary magnet 68 is positioned to receive respective mating molded sections 80a and 80b extending from respective inner front and rear walls 82a and'82b of molded half section 14a as shown in FIG. 3, and half of each beveled end 26a and 26b of movable magnet 20 rests on respective molded beveled receiving sections 84a and 84b extending from the inner surfaces of the respective front and rear walls of lower molded half section 14a. Lower molded half section 14b is then fastened to base plate 12, using standard fastening means such as a screw 86 (shown in FIG. 1) which passes through tapped holes in the base plate and a portion of lower half section 14b, so that another end 88 of operating coil 62 is positioned to rest on a lower ledge 89 of a window 90 formed within a side wall 91 of lower housing section 14b (shown in FIG. 2), while the remaining halves of beveled ends 26a and 26b of movable magnet and grooves 70a and 70b of stationary magnet 68 engage respective mating molded portions extending from the inner walls of lower half section 14b. Magnet 20, which is positioned for reciprocal movement within lower half sections 14d and 14b of the housing, will thus have its beveled ends 26a and 26b rest against the molded respective beveled receiving sections of the housing when the relay is deenergized, and when the relay is energized the magnet 20 moves upward within the housing until its pole faces a and 30b abut stationary magnet 68. As movable magnet 20 reciprocally moves Within the housing, arms 36a and 36b of rigid member 34 serve as a guide therefor.

A one piece yoke 92 shown in FIGS. 3 and 4 is located in an opening in the bottom of upper housing 16, and has overhanging sections 93a and 93b which extend respectively from upper portions of its opposite end surfaces. The overhanging sections of the yoke rest on respective ledges 94a and 94b at the bottom of upper housing section 16 so as to prevent the yoke from falling through the bottom of section 16. The top surface of yoke 92 has a plurality of hollow protruding sections 96 extending upwardly therefrom. The yoke also has a shaft 98 extending from the top surface thereof and through the upper end of housing section 16. Each of protruding sections 96 extends into a compartment 100 formed within molded upper housing section 16. Each compartment contains an enclosed switch module 102 (shown in FIGS. 5 and 6). Each switch module includes respective stationary contacts 104 and 105 fixed therewithin, an actuating plunger 106 which extends into and through an enclosure 107 of the switch module, a movable contact bridge 108 slidably attached via a compression spring 109 to actuating plunger 106, and respective pairs 110 and 111 of movable contacts, each pair being fixed to one of the ends of contact bridge 108 and in juxtaposition with respective stationary contacts 104 and 105. One end of each actuating plunger is positioned within each respective hollow section 96 of yoke 92. Yoke 92 is located above and in juxtaposition with respective actuating sections 56a and 56b of rigid member 34 so,that when the relay is energized, movable magnet 20 travels upward towards stationary magnet 68 and causes the actuating sections of the rigid member to push yoke 92 upward and thereby simultaneously actuate each of the switch modules. This one piece yoke 92 is less expensive than using individual parts for moving each actuating plunger of each switch module. Furthermore yoke 92 provides greater force against sticking normally closed contacts of a switch module than does individual parts or springs, and is thus more effective in breaking contact welds thereby preventing failure of the relay. If the yoke cannot break a welded normally closed set of contacts of a switch module when the relay is energized, the yoke will not move and will not actuate any of the other switch modules, thus rendering it easier to detect contact failure of any normally closed contacts of any switch module.

After each of the switch modules is assembled in its respective compartment, upper housing member 16 is fastened to lower housing sections 14a and 14b and housing cover 18 is fastened to upper housing section 16 using standard threaded fasteners 112, shown in FIG. 1. Housing cover 18 has contained therein a one piece spring loaded yoke cover 114 which forces the actuating plungers of each switch module downward to an unactuated position when the relay is deenergized. Yoke cover 114 provides greater force against sticking normally open contacts of a switch module than does separate springs for each module, and is thus more effective in breaking contact welds thereby preventing failure of the relay. If yoke cover 114 cannot break a set of welded normally open contacts of a switch module when the relay is deenergized, the yoke cover will not move and will not deactuate any of the other switch modules, thus rendering it easier to detect contact failure of any normally open contacts of any switch module. Spring loaded yoke cover 114 also forces shaft 98 of yoke 92 downward so that the bottom surface of yoke 92 in turn forces actuating sections 56a and 56b of rigid member 34 downward, and thus insures that magnet 20 moves to its deenergized position. At this point it should be noted that rigid member 34, which is in the form of a unitary structural piece, successfully serves the three fold purpose of forming the pole shaders for the movable magnet, guiding the movable magnet within the housing, and actuating the switch modules. Furthermore this one piece construction of rigid member 34 provides member 34 with good structural strength and enables utilization of a larger and more effective pole shader.

The switch module in the relay in FIGS. 1 and 2 is positioned to be in the normally closed contact mode such that when the relay is deenergized as shown in FIG. 1 its movable contacts 110 and 111 engage respective stationary contacts 104 and 105, and when the relay is energized as shown in FIG. 2 movable contacts 110 and l 11 respectively disengage stationary contacts 104 and 105. However, the switch modules used in this invention are of the reversible contact mode, wherein the actual contact mode depends upon how a switch module is placed in the relay. Thus, if the switch module is so placed within a compartment of housing 16 that stationary contacts 104 and are positioned above movable contacts and 111 as shown in FIG. 5, the switch module is positioned in the normally open contact mode.

Similarly, if the switch module is so placed in a compartment of the housing that the stationary contacts are positioned below the movable contacts as shown in FIG. 6, the switch module is positioned in the normally closed mode. External terminals 116 of the switch module, which are electrically and mechanically connected to the stationary contacts, are always positioned upright regardless of the contact mode of the switch module in the compartment so that the external electrical connection can be readily made to the external terminals.

In order to aid in the identification of the contact mode of the switch module after assembly of the relay is complete, module enclosure 107, which can be made from solid transparent plastic material, has protruding portions 118 extending from end surfaces 120 thereof and positioned closer to stationary contacts 104 and 105 than to movable contacts 1 10 and 1 l 1 as shown'in FIGS. 5 and 6. Of course portions 118 could be positionedcloser to movable contacts 110 and 111 than to stationary contacts 104 and 105. Protruding portions 118 are of a different color than the side of the switch modules enclosure so as to provide a good visual indication of the assigned contact mode when looking at the assembled relay. Thus if the switch module is placed in the housing of the relay in the position as shown in FIG. 5, the visual observance of protruding portions 118 will provide the indication that the switch module is positioned in the normally open contact mode, whereas if protruding portions 118 are not visible because they are being blocked by terminals 116 then the switch module will be known to be positioned in the normally closed contact mode as shown in P16. 6.

Normally when a pair of movable contacts attached to a symmetrically bifurcated end of the contact bridge are traveling in a direction to engage a respective stationary contact, a contact occurs in the form of a damped oscillation until at least one of the pair of movable contacts at each end of the contact bridge are both firmly engaging the respective stationary contact. If

each of the movable contacts at both ends of the contact bridge are bouncing at the same time, final contact closure is delayed, causing excessive contact arcing and contact erosion. In order to increase the response time of the switch during initial closure of the stationary and movable contacts, opposite ends 122a and l22b of contact bridge 108 are unsymmetrically bifurcated by respective slots 124a and 124b to form unsymmetric adjacent cantilevered fingers 126a and l26b at end 122a and unsymmetric adjacent cantilevered fingers 128a and 128b at end l22b of bridge 108 as shown in FIG. 7. As shown in FIGS. 7 and 8 contacts 130a and 130b of movable contact pair 110 are attached to the respective ends of fingers 126a and 12611. Also contacts 132a and 1321) of movable contact pair 111 are attached to the respective ends of fingers 128a and l28b. The mass of contacts 130a and l32b is greater than the mass of respective contacts 13% and 132a so that upon closure of the contacts of the switch module, contacts l30b and 132a bounce at a higher frequency ratethan contacts 130a and l32b. Thus the two movable contacts at each end of the contact bridge, which provide parallel electrical paths, have a non-synchronous bounce with respect to each other during contact closure so as to increase the probability of faster effective final contact closure of the switch module, thereby decreasing the chances of contact sticking and failure of the switch module and relay.

Although the invention has been described with reference to a specific embodiment thereof, numerous modifications are possible without departing from the invention and it is desirable to cover-all modifications falling within the spirit and scope of this invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. An electromagnetic switching device comprising:

a. a housing;

b. an operating coil having an opening therein positioned in said housing;

0. a stationary magnet positioned within the opening of said operating coil;

d. a movable magnet having a pair of pole faces and being mounted for reciprocal movement between an energized and a deenergized position within said housing;

e. switch means mounted in said housing;

f. means for actuating said switch means in response to movement of said movable magnet; and

g. a one piece rigid member including portions fixed to said pole faces and constituting a pole shader for said movable magnet, rigid arms extending in the direction of movement of said movable magnet for guiding said movable magnet in said housing between the energized and deenergized positions, and actuator sections extending from said arms in a direction away from said movable magnet for moving said actuating means when said device is energized.

2. A device according to claim 1 wherein said movable magnet is U-shaped and has a base and a pair of legs extending from said base, the ends of said legs distant from said base forming said pole faces, said legs having slots therein extending from said pole faces and into said respective legs for receiving saidportions of said rigid member which form said pole shader for said movable magnet.

3. A device according to claim 2 further comprising means for locking said rigid member to said movable magnet.

4. A device accordingto claim 3 wherein said base of said movable magnet has a passage therethrough for receiving said locking means for securing said rigid member to said movable magnet.

5. A device according to claim 4 wherein said arms of said rigid member are connected together via a pair of rigid base frame members, and each of said base frame members has a slot extending from a surface thereof for receiving said locking means for securing said movable magnet thereto.

6. A device according to claim 3 wherein said locking means comprises a flat spring extending through the passage in the base of said movable magnet and having opposite ends thereof received in the respective slots in said base frame members of said rigid member.

7. A device according to claim 1 wherein each of said arms of said rigid member has a window therein.

8. A device according to claim 7 wherein opposite ends of said stationary magnet extend through the respective windows in said arms of said rigid member.

9. A device according to claim 1 wherein said actuating means is comprised of a one piece yoke, said yoke including a yoke base and a shaft extending from said yoke base through an opening in said housing, said yoke base having a bottom surface engaging said actuator sections of said rigid member, a top surface of said yoke base having a plurality of raised sections, each of said raised sections engaging said switch means whereby upon energization of said operating coil, said movable magnet moves in a direction toward said stationary magnet to the energized position thereby causing said actuator sections of said rigid member to move said yoke and actuate said switch means.

10. A switching device according to claim 9 further comprising spring loaded means for deactuating said switch means and moving said shaft of said yoke in a direction to cause said actuator sections of said rigid member and said movable magnet to move to the deenergized position when said operating coil is deenergized.

11. A switching device according -to claim 1 wherein said switch means is comprised of a plurality of switch modules, each module including an enclosure, a pair of stationary contacts, an actuating plunger, a contact carrier bridge mounted on said plunger, and a first and a second pair of adjacent movable contacts, each said pair of movable contacts being attached to a respective end of said bridge in juxtaposition with a respective one of said stationary contacts.

12. A switching device according to claim 1 1 wherein opposite ends of said bridge are unsymmetrically bifurcated and one contact of each said pair of movable contacts has a mass unequal to the mass of its other adjacent contact so as to cause the adjacent contacts of each said pair of movable contacts to have a nonsynchronized bounce during closure of said stationary and movable contacts.

13. A switching device according to claim 1 1 wherein said enclosure of said switch module is comprised of a pair of opposite end surfaces, a first surface adjacent said end surfaces, and a second surface opposite said first surface.

14. A switching device according to claim 13 wherein said first surface of said enclosure is closer to said stationary contacts than to said movable contacts and said second surface of said enclosure is closer to said movable contacts than to said stationary contacts, whereby when said switch module is positioned in said housing of said relay such that said yoke is closer to said second surface than said first surface said switch module is mounted in a normally open contact mode, and when said switch module is mounted in said housing such that said yoke is closer to said first surface than said second surface said switch module is in a normally closed contact mode.

15. A switching device according to claim 14 wherein said enclosure includes first and second protruding portions extending from said respective end surfaces and adjacent one of said first and second surfaces, said protruding portions being of a contrasting color to the color of said end surface and visible from a position exterior of said switching device so as to provide a visual indication of the contact mode of said switch module mounted in said housing.

16. An enclosure for a switch having reversible contact modes, said switch including a pair of stationary contacts within said enclosure, an actuating plunger movable within and extending from said enclosure, a

contact bridge attached to said plunger, and movable contacts attached to opposite ends of said bridge and in juxtaposition with said stationary contacts, a pair of contact terminals external of said enclosure and electrically connected to said stationary contacts, said enclosure having a pair of end surfaces, a first surface adjacent each of said end surfaces, and a second surface opcent one of said first and second surfaces, said protruding portions providing a visual indication for determining whether said switch is positioned in the normally closed contact mode.

17. An enclosure for a switch according to claim 16 wherein said protruding portions are of a color different to the color of said end surfaces of said housing as to provide a visual indication for determining the contact mode of said switch.

18. An electromagnetic switching device comprising:

a. a movable magnet having at least one pole face and being mounted for reciprocal movement between an energized and a deenergized position;

b. a stationary magnet in juxtaposition with said movable magnet;

c. an operating coil for energizing said device;

d. switch means;

e. means for actuating said switch means in response to movement of said movable magnet; and

f. a one piece rigid member including portions fixed to said pole face and constituting a pole shader for said movable magnet, rigid arms extending in the direction of movement of said movable magnet for guiding said movable magnet between the energized and deenergized positions, and actuator sections extending from said arms in a direction away I from said movable magnet for moving said actuating means when said device is energized.

19. An electromagnetic switching device comprising:

a. a housing;

b. an operating coil having an opening therein positioned in said housing;

c. a stationary magnet positioned within the opening in said operating coil;

d. a movable magnet mounted for reciprocal movement between an energized and a deenergized position within said housing;

e. a plurality of switch modules mounted in said housing, each of said switch modules having an enclosure and an actuating plunger extending through opposite ends of said enclosure;

f. a one piece yoke for simultaneously moving one end of each of said actuating plungers to actuate said switch modules upon energization of said device;

g. means for moving said yoke upon energization of said device and movement of said movable magnet to said energized position; and

h. a spring loaded yoke cover engaging the opposite end of each of said actuating plungers of each of said switch modules for simultaneously moving each of said actuating plungers to deactuate said switch modules upon deenergization of said device.

of a respective one of said actuating plungers. 

1. An electromagnetic switching device comprising: a. a housing; b. an operating coil having an opening therein positioned in said housing; c. a stationary magnet positioned within the opening of said operating coil; d. a movable magnet having a pair of pole faces and being mounted for reciprocal movement between an energized and a deenergized position within said housing; e. switch means mounted in said housing; f. means for actuating said switch means in response to movement of said movable magnet; and g. a one piece rigid member including portions fixed to said pole faces and constituting a pole shader for said movable magnet, rigid arms extending in the direction of movement of said movable magnet for guiding said movable magnet in said housing between the energized and deenergized positions, and actuator sections extending from said arms in a direction away from said movable magnet for moving said actuating means when said device is energized.
 2. A device according to claim 1 wherein said movable magnet is U-shaped and has a base and a pair of legs extending from said base, the ends of said legs distant from said base forming said pole faces, said legs having slots therein extending from said pole faces and into said respective legs for receiving said portions of said rigid member which form said pole shader for said movable magnet.
 3. A device according to claim 2 further comprising means for locking said rigid member to said movable magnet.
 4. A device according to claim 3 wherein said base of said movable magnet has a passage therethrough for receiving said locking means for securing said rigid member to said movable magnet.
 5. A device according to claim 4 wherein said arms of said rigid member are connected together via a pair of rigid base frame members, and each of said base frame members has a slot extending from a surface thereof for receiving said locking means for securing said movable magnet thereto.
 6. A device according to claim 3 wherein said locking means comprises a flat spring extending through the passage in the base of said movable magnet and having opposite ends thereof received in the respective slots in said base frame members of said rigid member.
 7. A device according to claim 1 wherein each of said arms of said rigid member has a window therein.
 8. A device according to claim 7 wherein opposite ends of said stationary magnet extend through the respective windows in said arms of said rigid member.
 9. A device according to claim 1 wherein said actuating means is comprised of a one piece yoke, said yoke including a yoke base and a shaft extending from said yoke base through an opening in said housing, said yoke base having a bottom surface engaging said actuator sections of said rigid member, a top surface of said yoke base having a plurality of raised sections, each of said raised sections engaging said switch means whereby upon energization of said operating coil, said movable magnet moves in a direction toward said stationary magnet to the energized position thereby causing said actuator sections of said rigid member to move said yoke and actuate said switch means.
 10. A switching device according to claim 9 further comprising spring loaded means for deactuating said switch means and moving said shaft of said yoke in a direction to cause said actuator sections of said rigid member and said movable magnet to move to the deenergized position when said operating coil is deenergized.
 11. A switching device according to claim 1 wherein said switch means is comprised of a plurality of switch modules, each module including an enclosure, a pair of stationary contacts, an actuating plunger, a contact carrier bridge mounted on said plunger, and a first and a second pair of adjacent movable contacts, each said pair of movable contacts being attached to a respective end of said bridge in juxtaposition with a respective one of said stationary contacts.
 12. A switching device according to claim 11 wherein opposite ends of said bridge are unsymmetrically bifurcated and one contact of each said pair of movable contacts has a mass unequal to the mass of its other adjacent contact so as to cause the adjacent contacts of each said pair of movable contacts to have a non-synchronized bounce during closure of said stationary and movable contacts.
 13. A switching device according to claim 11 wherein said enclosure of said switch module is comprised of a pair of opposite end surfaces, a first surface adjacent said end surfaces, and a second surface opposite said first surface.
 14. A switching device according to claim 13 wherein said first surface of said enclosure is closer to said stationary contacts than to said movable contacts and said second surface of said enclosure is closer to said movable contacts than to said stationary contacts, whereby when said switch module is positioned in said housing of said relay such that said yoke is closer to said second surface than said first surface said switch module is mounted in a normally open contact mode, and when said switch module is mounted in said housing such that said yoke is closer to said first surface than said second surface said switch module is in a normally closed contact mode.
 15. A switching device according to claim 14 wherein said enclosure includes first and second protruding portions extending from said respective end surfaces and adjacent one of said first and second surfaces, said protruding portions being of a contrasting color to the color of said end surface and visible from a position exterior of said switching device so as to provide a visual indication of the contact mode of said switch module mounted in said housing.
 16. An enclosure for a switch having reversible contact modes, said switch including a pair of stationary contacts within said enclosure, an actuating plunger movable within and extending from said enclosure, a contact bridge attached to said plunger, and movable contacts attached to opposite ends of said bridge and in juxtaposition with said stationary contacts, a pair of contact terminals external of said enclosure and electrically connected to said stationary contacts, said enclosure having a pair of end surfaces, a first surface adjacent each of said end surfaces, and a second surface opposite said first surface, said first surface being closer to said stationary contacts than to said movable contacts and said second surface being closer to said movable contacts than to said stationary contacts whereby when said first surface is positioned above said second surface said switch is in a normally open contact mode and when said second surface is positioneD above said first surface said switch is in a normally closed contact mode, wherein the improvement comprises a pair of protruding portions extending from said respective end surfaces of said enclosure and adjacent one of said first and second surfaces, said protruding portions providing a visual indication for determining whether said switch is positioned in the normally closed contact mode.
 17. An enclosure for a switch according to claim 16 wherein said protruding portions are of a color different to the color of said end surfaces of said housing as to provide a visual indication for determining the contact mode of said switch.
 18. An electromagnetic switching device comprising: a. a movable magnet having at least one pole face and being mounted for reciprocal movement between an energized and a deenergized position; b. a stationary magnet in juxtaposition with said movable magnet; c. an operating coil for energizing said device; d. switch means; e. means for actuating said switch means in response to movement of said movable magnet; and f. a one piece rigid member including portions fixed to said pole face and constituting a pole shader for said movable magnet, rigid arms extending in the direction of movement of said movable magnet for guiding said movable magnet between the energized and deenergized positions, and actuator sections extending from said arms in a direction away from said movable magnet for moving said actuating means when said device is energized.
 19. An electromagnetic switching device comprising: a. a housing; b. an operating coil having an opening therein positioned in said housing; c. a stationary magnet positioned within the opening in said operating coil; d. a movable magnet mounted for reciprocal movement between an energized and a deenergized position within said housing; e. a plurality of switch modules mounted in said housing, each of said switch modules having an enclosure and an actuating plunger extending through opposite ends of said enclosure; f. a one piece yoke for simultaneously moving one end of each of said actuating plungers to actuate said switch modules upon energization of said device; g. means for moving said yoke upon energization of said device and movement of said movable magnet to said energized position; and h. a spring loaded yoke cover engaging the opposite end of each of said actuating plungers of each of said switch modules for simultaneously moving each of said actuating plungers to deactuate said switch modules upon deenergization of said device.
 20. An electromagnetic device according to claim 19 wherein said yoke includes a plurality of raised sections, each of said raised sections engaging said one end of a respective one of said actuating plungers. 